1. Field of the Invention
The present invention relates to a radio receiver for selective calling that receives time information by radio and corrects the time of an incorporated clock, and in particular to a radio receiver for selective calling that can save on battery usage and can reduce the possibility that an incorrect time will be received and displayed.
2. Related Arts
Some systems for a radio receiver for selective calling periodically receive time information by radio.
FIG. 6 is a timing chart showing the timing for time corrections employed for a conventional radio receiver for selective calling. Time information is transmitted in the frame "0," shown in FIG. 6A, the processing for this being shown in FIG. 6B. Other information is transmitted in the other frames.
Conventionally, a radio receiver for selective calling receives time information in each time frame "0" is transmitted, and corrects the time displayed by an incorporated clock, as is shown in FIG. 6C.
For a current radio receiver for selective calling, generally a technique called a battery saving function is employed in order to extend the service life of an incorporated battery.
According to this technique, a frame for self-calling is determined in advance to be frame "27," for example, and at a time other than the time of transmission of frame "27," the radio receiver for selective calling disconnects a power supply for a reception section or the like.
In the conventional radio receiver for selective calling, however, the power source for the reception section is turned on upon each transmission of time information (frame "0"), in addition to the transmission time for the frame for self-calling. As a result, the efficiency of the battery saving function is deteriorated.
In addition, since the time is corrected upon each transmission of time information, time correction is constantly performed in an area where a reception barrier occurs, even when incorrect time information is received, so that an incorrect time is frequently displayed.